Just one little tip that is a help...if you are leaking down a motor with some time on it or even a new one put a piece of tape over the 3/5 and the 4/6 exhaust port when you do the one next to it and if the tape blows you have a bad head gasket. Just a little way to check the head gasket at the same time.:thumb you need to have the rockers backed off to do this though